1. Field of the Invention
The present invention relates to a display element which has two display surfaces, for example, of different colors, and magnetic pieces and is rotatable about the axis of its own, and a display panel which has a display surface structure having a number of such display elements arranged to provide a display of a letter, graph, pattern or the like in a predetermined plane.
2. Description of the Prior Art
Heretofore, there has been proposed a display panel of the type producing a display of a desired letter, graph, pattern or the like in two colors by a display surface structure having arranged thereon a number of magnetically rotatable display elements, each having two display surfaces of different colors.
The display element for use in such a display panel is formed by a plate-like member the front and the back side of which form display surfaces of different colors and has a magnetic piece disposed at one of two edges defined by the two display surfaces. For selectively turning such a display element, the display panel has a display switching unit provided with a magnetic head formed by an electromagnet which acts on the magnetic piece of the display element while moving relative thereto.
With the conventional display panel using such display element, however, a display is erased as one magnetic head is moved in one direction (upwardly, for instance,) relative to the display element and then a display is written as the magnetic head is moved in the opposite direction (downwardly, for example). Therefore, the display erasing and writing operation is time-consuming.
Moreover, in the case where the display panel is arranged so that the display element is supported in a manner to be rotatable about a shaft extending in a horizontal direction, and that a magnetic head erases a display and writes a new display while moving up and down relative to the display element, even if the display element is plate-shaped, a shaft receiving hole is bored through the display element to extend along the display surfaces. A small-diametered shaft is loosely inserted into the shaft receiving hole and the display element is suspended from the shaft by the weight of its own. Accordingly, the display element is stably supported so that one of its two display surfaces may lie in a predetermined plane.
When it is desired that the display panel is arranged so that display element is supported rotatably about a shaft extending in a vertical direction and the magnetic head erases a display and writes a new display while moving horizontally relative to the display element, it is difficult to support the display element so that one of its two display surfaces may lie in the predetermined plane.
Besides, when the display element is the plate-shaped member the front and the back side of which form display surfaces, the display element is turned over an angular range of 180 degrees. Therefore, the shaft receiving hole of the display element and the shaft loosely inserted thereinto become worn after long use, resulting in malfunction of the display panel.